Question
Hilly areas receiving heavy rainfall, where a major portion of the rainfall is to be drained as surface runoff, are suggested to adopt bench terraces with ____________.
The correct answer is
sloping inward
Bench Terraces in Hilly, High-Rainfall Areas
Bench terraces are used in hilly regions to control soil erosion and manage water, especially when rainfall is heavy and a significant amount becomes surface runoff.
Terrace Surface Design for Runoff Management
The design of the terrace surface is critical for managing water flow:
- Level tops create a flat area but may hold excess water if not drained.
- Sloping outward would cause water to run off the edge, potentially increasing erosion.
- Narrow width is a dimension, not a surface characteristic for drainage.
- Sloping inward (towards the hill) helps retain rainwater on the terrace surface. This allows water to infiltrate the soil within the terrace, reducing the volume and speed of runoff that leaves the terrace system. This design is crucial for water conservation and preventing erosion in challenging conditions like heavy rainfall in hilly areas.
Conclusion on Terrace Features
For hilly areas receiving heavy rainfall where surface runoff is a major concern, bench terraces are recommended to have tops that slope inward. This feature aids in water retention and infiltration, minimizing destructive surface runoff.
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Important Questions from Terraces
- Bench terraces are planned on $15\%$ hill slope. The vertical interval is $2.5\text{ m}$, and the riser has a slope of $1:1$. The earthwork in cutting is equal to the earthwork in filling. The volume of earthwork per hectare (in $\text{m}^3\text{.ha}^{-1}$) is ________ (Rounded off to the nearest integer)
- If the width of bench terrace is W, drop D and existing land slope S; then for 150% batter slope, the drop D will be
- Bench terraces are to be constructed on a 15% hill slope. The batter slope is 1:1 and vertical interval is 2.5 m. The earth work in cutting is equal to filling. The quantum of earthwork in $m^3 ha^{-1}$ will be
- It is proposed to construct bench terraces on a 10% hill slope. If the batter slope is $\frac{1}{2} \text{ H} : 1 \text{ V}$, the percentage area that will be lost for cultivation due to bench terracing is
- For the eastern Himalayan region having hill slope of 16%, a bench terrace system is to be designed. It is found that the depth of cut for constructing the bench terrace cannot be more than 0.40 m due to the limitation of the soil depth. If a batter slope of $1\frac{1}{2}:1$ is proposed, the maximum possible width of the terrace and the required earthwork per hectare (assuming cut equal to fill) will be
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